jim.snowdon Posted January 11, 2017 Share Posted January 11, 2017 Digital calipers may read to 0.01mm, but they need some level of skill to achieve a measuring accuracy better than 0.05mm due to deflection of the calipers and keeping them square to the item being measured. There is nothing complicated with specifying tolerances. What it does is ensures compatibility between manufacturers of models and gauges. I fully agree, track gauges need to be made to reasonable standards. But what is a reasonable standard? What is close enough to the nominal value? The answer to these questions is only clearly defined using a properly toleranced standard. At the crossing V, the gauge tolerance is much smaller compared to plain track. Traditional H0/00 Gauges designed for crossing V construction need to have a track gauge of 16.55mm +/- 0.05mm, with a flange way lug of 1.25mm +/- 0.05mm to achieve a suitable span and check gauge for RTR wheels. I'm familiar with checking and calibration of measuring equipment, as I was employed for a couple of years as a standards officer in the NSW standards laboratory. I am currently the officer in charge of a Universities Metrology laboratory. I think I have a reasonable grasp of how to measure and build model railway gauges, wheels and track. Cheers, Terry Flynn. Terry, I think we have it in a nutshell. You are, by training an metrologist, ie in the business of measurement precision. I am, by training, an engineer, and as such interested in what will make things work. A consequence of that is that I am interested in the limits within which our wheels and track will work with each other, rather than the precise tolerancing of a set of dimensions that are within those limits. Part of that is knowing how far you can depart from the ideal before, in our case, the perfomance of the rolling stock starts to suffer noticeably. Jim Link to post Share on other sites More sharing options...
Junctionmad Posted January 11, 2017 Share Posted January 11, 2017 As a track builder , I find myself in complete agreement with Martin. The two relevant gauges are flangeway and check gauge , obviously one must keep the track gauge within limits , but the fact remains variations in it have little effect Whether wooden gauges etc are acceptable , remains within the realms of a curiosity as I've never met anyone using them. Making a metal gauge ( or buying one ) is not complex. Given my track intentionally varies from 16.5 nominal to 16.2 nominal I suggest the gauge is not " that " important Note , I'd suggest P4 is easier to build because of the smaller number of " standards " and the fact that things like crossovers are easier to build. Ps : could I suggest that to avoid pissing contests , that telling me that professional railway engineers have any relevance to model railways , is rather like a brickie advising on building a model station. !!! ( a toolmaker , metrologist and a railway engineer walked into a bar .......) That's the great thing about standards , there's so many to choose from The other issue being missed here , is that most builders use gauges as jigs rather then gauges. Furthermore AMRA, DOGA. Etc , Don't produce standards , they produce specifications , standards are standards because they are widely accepted and adopted. Specifications are something you'd like people to follow. Peco is a standard and is not a specification, RP-25 100 is both as its widely adopted to be judged a standard , DOGA is not a standard. I do however agree with bertiedog, gauges only need to be precise/accurate " enough " , even in p4. Many builders do not achive " thou " accuracies all through a typical turnout even in p4. Some time ago , when I did a fair bit of copper clad , I built a few p4 points , I didn't find it much different to building 00 ones. The process was the same, the rail was code 75 and the gauges were the same type albeit wider. It did seem less tolerant of poor installation more then build accuracy. Link to post Share on other sites More sharing options...
hayfield Posted January 12, 2017 Share Posted January 12, 2017 Ps : could I suggest that to avoid pissing contests , that telling me that professional railway engineers have any relevance to model railways , is rather like a brickie advising on building a model station. !!! ( a toolmaker , metrologist and a railway engineer walked into a bar .......) But if they happen to be both a modeller and a supplier of model making parts, I might be tempted to listen to them. Lets face it we are hardly building a jet engine !! Link to post Share on other sites More sharing options...
bertiedog Posted January 12, 2017 Author Share Posted January 12, 2017 Mention is made that the gauge standard of accuracy is not that important and that is true on track, but it is vital to the spacing of the flangeways in points, where they must be in relation to the rails, and you have to assume the gauge is correct, or your heading for troubles. In model railways terms a Gauge and a Jig are interchangeable, lets not make it complex. Also the use of wood was suggested as I have used steel pins in wood many times, but usually make a jig in brass in about 5 minutes, checking with a vernier caliper. On speed of working to get a sound point, I have just made four for 009 gauge and they took two evenings to complete on PC sleepers, The running through them is smooth and drop free, and the action light as there is a phosphor bronze strip hinge in the blade, looks solid at set road, only bending the hinge on the dead switch blade. The testing showed up problems with two Peco items for the L&B stock, they needed the back to back re-set . Last night I did a custom curved point for the Brewery layout, at 9 inch inner radius, 16 outer, in code 75 flat bottom on PC sleeper in about 2 hours to test and fitting. Because of the tight curves the Hornby Peckett and 4 wheels stock can take, the crossing is done with fully curved parts. I used no gauges at all, just the vernier, and again the operation is smooth, the loco barely notices the point, with stock wheels just making a faint click as they go over the crossing V. It varies with different makers wheels as wide tyres run better over a frog. The PC construction was allowed as the points are to be buried in cobbles, so no chairs needed. Also I did a couple of more conventional large radius points in C&L and Exacto chairs, with plastic sleepers, these took about 3 hours each, again no jigs, except to fit into the flange way to glue in the half chairs on the checkrails. No issues except the cost of the sleepers, which in future I am replacing with Plasticard in black, epoxy glued to a sheet of thin ply and then sawn up in my bench top bandsaw. It provides a better choice of lengths. The grain is done with a wire brush. Running is perfect, nothing unusual, as long as the wheels are compliant to something near the RP-25 spec. Very narrow tyres drop a fraction, all modern RTR sails through the points. These longer ones have no hinge fitted, solid except for insulation, with switch blades electrically bonded to the stock rail, to be able to reduce the clearances as much as possible when the rails move on switching. The chaired version is not to P4 standards as to the correct chairs exactly in each position, greatly simplified to just chairs and sliding chairs, plus half chairs cut from whole ones. The check rails are supported by p/b strips from the running rails, covered by the half chairs. Stephen Link to post Share on other sites More sharing options...
alastairq Posted January 12, 2017 Share Posted January 12, 2017 Lordy...even the rail itself isn't guaranteed to be 'Code-whatever-it-is''......I have recently measured some random bits of rail, and was surprised to find that some of the code 80[2?] was nearer the top end of some of the code 75! The only real way I could tell...having got it all mixed up during moves....was by the obvious width of the foot, and whether it was bullhead, or flatbottom! I have used wood for a 'gauge',,for the main reason, as was mentioned above, as a jig to actually 'hold' the rail..... Stability of the wood used wasn't even considered....ie, a piece of ramin, or something like....a couple of slots cut pretty much to the gauge required, to hold the rail had....then used..then lost in the mists of time, never to be seen again. Then found, and used for a truck bolster or two! A case of 'needs-must' at the time.....?? Link to post Share on other sites More sharing options...
meil Posted January 12, 2017 Share Posted January 12, 2017 Mention is made that the gauge standard of accuracy is not that important and that is true on track, but it is vital to the spacing of the flangeways in points, where they must be in relation to the rails, and you have to assume the gauge is correct, or your heading for troubles. Stephen Of dear you really don't understand how to construct a crossing. The only flangeway that is important is the one adjacent to the crossing nose. The flangeway at the check rail is what ever it is after you have set the check-gauge. Link to post Share on other sites More sharing options...
jim.snowdon Posted January 12, 2017 Share Posted January 12, 2017 Mention is made that the gauge standard of accuracy is not that important and that is true on track, but it is vital to the spacing of the flangeways in points, where they must be in relation to the rails, and you have to assume the gauge is correct, or your heading for troubles. In model railways terms a Gauge and a Jig are interchangeable, lets not make it complex. Stephen Stephen, If you set the check rail by reference to the adjacent running rail, using a flangeway gauge, its as-built position will be determined by the construction tolerances in both the track gauge and the check rail setting. Whilst this approach is acceptable for the prototype, it is in a context where the gauge can be set within millimetres and the check flangeway is set to similar accuracy by cast iron spacer blocks and/or special chairs/baseplates, ie to tolerances that are propartionately far higher than anything we can achieve in our models. For us, the proper approach to setting the check rail position is by gauging it from the crossing rails, when any errors in the as-built track gauge do not matter. The flangeway gauge is really only of use in the construction of the crossing itself in setting the gaps at the crossing nose. Jim Link to post Share on other sites More sharing options...
bertiedog Posted January 12, 2017 Author Share Posted January 12, 2017 Oh well, I will have to check the possible thousands or so points I have made, but the flangeways are identical width if the track gauge is correct, and if the stock has the correct wheel shape and back to back. How can a situation arise that the flangeways are odd for some reason, if the check rail is further out, then the wheelset will risk running into the crossing V nose, the only thing stopping it would be the curved root of the flange to the tyre. If the flangeway between the stock rail and the check rail can be adjusted then by how much and on what basis is it calculated on? I know there are practical tolerances on the dimensions but biasing or using the tolerances to move the rail surely is wrong? I expect there are situations in real track that will involve adjustments, but not to a model track. As the wheel passes over the crossing it is supported by the outer edge of the tyre, in the same way as the tyre approaches the nose gap, in pratice the wheel sold behave as though the nose gap was not there, guided by the coned tyre and root curve placing the wheel in the correct position to pass the nose. The check rail at the correct position will stop the wheel hitting the nose, especially on tight radius points, where the flange on a 4 wheeled Loco or truck is not actually parallel with the rail, aggravating the problem slightly. Helping out other modellers with points over the years the most common fault is not having the flangeways identical, perhaps easing parts to get the point running with PC track, and not checking that the correction has altered the gauge or moved other parts. None of this is meant as a correction or not saying that other ways work, but I cannot see how altering the flangeways to different dimensions will help. However I do assemble the points a bit tight around the frog or crossing and then use a fine file to "fettle" or refine the rail till the gauge or the vernier show the exact correct figures, as I find the rail sections are not made to particularly fine tolerances on width, they can be up or down about 5 thou to 6 thou, I have had more! But by the time the point is finished I can guarantee the tip of the crossing, on the face towards the other stock rail is exactly 16,5, and the flangeways are equally spaced plus or minus a couple of thou......at which point the crossing behaves as though it is not there, which is the whole reason to build the point accurately. Stephen Link to post Share on other sites More sharing options...
RMweb Gold martin_wynne Posted January 12, 2017 RMweb Gold Share Posted January 12, 2017 How can a situation arise that the flangeways are odd for some reason Hi Stephen, Where there is gauge-widening, the flangeway at the check rail increases by the same amount as the widening. The prototype provides special check rail chairs for this purpose. The function of a check rail is determined by its distance from the nose of the crossing, and it therefore makes sense to set its position from the nose of the crossing. And not from the adjacent running rail. On a model gauge-widening is sometimes intentional for sharp curves, and sometimes arises from natural tolerances in construction and the fit of the rail in the gauges. If the check rail has been correctly set from the crossing with a check gauge tool, such variances in track gauge are of no great consequence. The check gauge is the critical dimension in pointwork, and the only way to get it right is to set it from the crossing. Some modellers like to fit the check rails before the stock rails for this reason - see several topics on RMweb. regards, Martin. Link to post Share on other sites More sharing options...
bertiedog Posted January 12, 2017 Author Share Posted January 12, 2017 Stephen, If you set the check rail by reference to the adjacent running rail, using a flangeway gauge, its as-built position will be determined by the construction tolerances in both the track gauge and the check rail setting. Whilst this approach is acceptable for the prototype, it is in a context where the gauge can be set within millimetres and the check flangeway is set to similar accuracy by cast iron spacer blocks and/or special chairs/baseplates, ie to tolerances that are propartionately far higher than anything we can achieve in our models. For us, the proper approach to setting the check rail position is by gauging it from the crossing rails, when any errors in the as-built track gauge do not matter. The flangeway gauge is really only of use in the construction of the crossing itself in setting the gaps at the crossing nose. Jim I think this is where the debate is going, you are assembling to allow for a possible problem with the track gauge and yes it can be measured from the crossing face to the flangeway face.and then the exact gauge does not matter at that point. My point is that the track gauge is the easiest dimension to set, it must be 16.5 throughout the point, easily achieved with a gauge, jig or vernier. Don't start adopting corrective assembly just to allow for the gauge to be a little bit wrong, as it is so easy to get it right. I tend to think that points work best when they are simply "Not There" to the stock running over them, bar the change in direction etc., over the blades and crossing V. I modelled in H0 for many years and stuck to the NMRA track standards and wheels and points never gave troubles, yet the MRC members I met using UK stock had woes beyond belief with points, mainly due to the awful UK wheelsets made then, no standards. So often they had troubles with PC points, most gave up and returned to Peco. When my H0 layout was displayed at shows, many commented on the smooth running through the points, often taking the commonly held belief that it is all due to US stock running on bogies. But I always took a rake of UK wagons and a 4F 060 along to shows and rang those with equal smoothness over the pointwork. It is nothing to do with the bogies or wheel sizes, it is all down to the track gauge being exact at all positions through the point and flangeways matching precisely to the appropriate standards for the wheels. There are other reasons to alter the structure of the point, but they are for appearance or very specialist copying of a real point in say P4. I have used Code 75 Peco points more as I have difficulty till recently with arthritis in the hands, and a near useless left arm, which meant it was easier to use RTR. but the performance is not really up to what I had expected, they do fiddle with the dimensions, but at least the basic correct stock wheels will operate through them without too much issue with drops etc. Stephen Link to post Share on other sites More sharing options...
bertiedog Posted January 12, 2017 Author Share Posted January 12, 2017 I know all about gauge widening in P4 etc., and apply it, but is it really needed in decently long, or large radius points in 00, where the fit of the wheels into the gauge is very slack indeed, and usually only comes into play when making track to prevent the closure of the gauge on tight curves, there is barely a need to gauge widen till you approach under 15 inches, which is a really tight curve for longer wheel based locos. When I make tram track this is gauge widened as the curves go down to 4 inches, but even then it is very minimal, up to .2 of a mm. This was not true tram track, but used conventional rail sections, rather than the flange running in a groove. The back to back was left at 14.5, after experiments with 14.6 etc, trying to stop too much waddle with such short wheelbase trams. But the adjustment made the points worst, and was soon dropped. Stephen Link to post Share on other sites More sharing options...
RMweb Gold martin_wynne Posted January 12, 2017 RMweb Gold Share Posted January 12, 2017 I know all about gauge widening in P4 etc., and apply it, but is it really needed in decently long, or large radius points in 00, where the fit of the wheels into the gauge is very slack indeed Hi Stephen, Not needed for 16.5mm gauge. That gauge already includes sufficient widening for sharp curves -- that's why as you say there is a lot of slop in the wheel fit. But a great many builders of 00 track now use 16.2mm gauge for improved running without that slop -- see http://4-sf.uk In that case some gauge-widening is desirable below about 30" radius, and 3-point track gauges are available from C&L for the purpose. If such radii occur within pointwork then the gauge-widening is needed there too, and the check rail flangeway must be increased by the same amount. All this is taken care of using the gauges available from C&L for 00-SF. regards, Martin. Link to post Share on other sites More sharing options...
Junctionmad Posted January 12, 2017 Share Posted January 12, 2017 Again , Stephen, I believe you are in the minority of track builders, When I first started building coper clad, I did as you did , focussing on gauge through the point, and setting the flange way gaps using a shim from each rail. In my case I ran the sequence from the straight stock rail , i.e. straight rail->crossing -> curved rail->nose flange way , stock rail flange way My experience was that I required quite precise position on a paper template to get that to work right , as it was awkward enough to to correctly gauge the curved rail so that the closure and switch blades ended up in gauge Then I switched to first fixing the crossing , and the closure rails and then seeking to track gauge the straight and curved stock rails . This proved to be better, though sometimes my straight rail was slightly off the template, but the point itself was fine . Again I gauged flange ways from the adjacent stock rail However I always found , I had to fettle the check rail positions to get the running correct , this was easy of course in copper clad, and at the time I thought this was a necessary step. I never considered check rail gauges Recently I returned to point building using plastic sleepers with pre-assembled crossings. ( and thanks to John etc ) . I now tend to lay the straight rail per the template ( and a straight edge ) , position the "V" from the straight rail and gauge the curved rail from the "V", but crucially I use a check gauge to set the stock rail check rail and a shim to set the crossing flange way . I gauge the closure rails from the stock rails. measuring the stock rail flange way gap, over a few points does show variances , possible because the rail distance isnt extremely accurate , but crucially the check rail distance and crossing flange way are as accurate as the gauges and its these two measurements that need to goo running. The fact that the gauge of the point , especially in 00 meanders a bit is of little issue. as I now build 00-SF points , its intentionally meanders ,!!! In reality this discussion , is an " angels on the head of a pin" argument, Built carefully , any method of track construction produces a point that is acceptable. The issue is to pick a method that is the most tolerant of construction errors and in that the check gauge approach is better in my opinion Link to post Share on other sites More sharing options...
RBAGE Posted January 12, 2017 Share Posted January 12, 2017 Here's my thought. I like the notion of assembling the common crossing separately. EMGS do a crossing jig and I thought I'd use the same principles for 7mm: I consists of a pair of 1x2" offcuts. I sandwiched brass strip, doubled up to ~ 1.75mm thick (flangeway) and plastic strip. The plastic sheet is 1mm thick, same as copperclad strip used to join the crossing together. The vee is made, then the wing rails are bent to shape. The vee is laid against the pins and clamped using spring clips. Use a flangeway gauge to space the first wing rail, laying it against the uprights. Solder to 1mm copper clad strip. The opposite side is assembled in a similar way. The important consideration is that the two flangeways through the crossing are accurately aligned. Trim the excess CC strip. I'm pretty happy with the results. John I like this very much. It would either save a great deal of cash if buying common crossings already made or save a great deal of heartache trying to maintain alignment through the crosing. Does anyone make such a gauge? Other than EM, that is. Link to post Share on other sites More sharing options...
RBAGE Posted January 12, 2017 Share Posted January 12, 2017 Steady on Jim. That's not my work. I would love to jump on the band wagon if someone want to start making them. First order here please. Link to post Share on other sites More sharing options...
Grovenor Posted January 12, 2017 Share Posted January 12, 2017 Does anyone make such a gauge? Other than EM, that is. Well, an EM one would be equally good for 00SF or any standard with a 1 mm flangeway, but they are simple to DIY build as is shown above. Regards Link to post Share on other sites More sharing options...
RBAGE Posted January 12, 2017 Share Posted January 12, 2017 Well, an EM one would be equally good for 00SF or any standard with a 1 mm flangeway, but they are simple to DIY build as is shown above. Regards Yes, I must have a go. Link to post Share on other sites More sharing options...
bertiedog Posted January 12, 2017 Author Share Posted January 12, 2017 Well, I still think the gauge of the track is vital, and easily set accurately, and adjusting it to the crossing is odd, as the two tracks path superimposed over each other determine the position of tip of the frog plus or minus nothing. or as near as practical work and measuring will allow. If the gauge has to be set to the crossing, the crossing is in the wrong position. I can't be doing much wrong if the point works all the time, with both say an 040 or a Pacific, and a mix of stock. And all the US ones work fine, the points are there as ghosts, the stock does not react to the crossing drop or the checkrail, apart from clicks on the gaps etc., and recently I tend to close those with epoxy. I should add that some US tyres are narrower than the days of Central Valley,and do drop slightly on the crossing, no risk other than a click. Stephen Stephen. Link to post Share on other sites More sharing options...
RMweb Premium Izzy Posted January 13, 2017 RMweb Premium Share Posted January 13, 2017 I like this very much. It would either save a great deal of cash if buying common crossings already made or save a great deal of heartache trying to maintain alignment through the crosing. Does anyone make such a gauge? Other than EM, that is. The 2mm scale association produce crossing jigs into which all the rails are formed, dropped, and then soldered together with ties of some kind, a method of sub-assembly that can be used with both soldered and chaired trackwork. More recently they have produced cast N/S crossing units to make life easier for those not at ease with producing the crossings, similar to thse made by British Finescale: http://www.britishfinescale.com/ Well, I still think the gauge of the track is vital, and easily set accurately, and adjusting it to the crossing is odd, as the two tracks path superimposed over each other determine the position of tip of the frog plus or minus nothing. or as near as practical work and measuring will allow. If the gauge has to be set to the crossing, the crossing is in the wrong position. I can't be doing much wrong if the point works all the time, with both say an 040 or a Pacific, and a mix of stock. And all the US ones work fine, the points are there as ghosts, the stock does not react to the crossing drop or the checkrail, apart from clicks on the gaps etc., and recently I tend to close those with epoxy. I should add that some US tyres are narrower than the days of Central Valley,and do drop slightly on the crossing, no risk other than a click. Stephen Stephen. I can see both sides of the discussion, but agree with Stephen that if the stock rail is gauged correctly from the crossing nose then all the rest should fall into place reasonably well. I have always used this old check rail gauge from the S4 society for my P4 track, (I haven't used any other gauge in 4mm since the late 1970's), and this can be used to both set the check rails and wing rails at the correct distance from the crossing. It also ensures the stock rail is not under-gauged from the crossing. I believe similar gauges are made for other scales/gauges, certainly 2mm, in which I currently mainly work. You'll forgive the less than perfect trackwork I hope. It is simply built using just ordinary chairs, cut up where needed, along with slide chairs. The only viable option back in the days before special chairs became available. My first P4 layout with chaired track used just the S4 cast whitemetal chairs, there were no slide chairs for them as they were meant purely for cosmetic use. But it worked out okay. I have never used check rail chairs either. These seem to fly in the face of setting the check rails using gauges, and are only viable - with no adjustment/fettling possible - if the stock rail is perfectly gauged from the crossing. Which brings us back to the begining.........all swings and roundabouts. regards, Izzy Link to post Share on other sites More sharing options...
bertiedog Posted January 13, 2017 Author Share Posted January 13, 2017 It is indeed swings and roundabouts, it works both ways, but I think for points that involved a curved route through them, the most commonly used in models to save space, the datum is the track course, and the crossing is fitted exactly where it has to go, +/- nothing, aided by precise gauging and nothing else. The pre building of a standard crossing with a fixed angle is quite different, the crossing becomes the datum for the measurements, and governs where the outer rails are laid, therefore very precise per planning and plan printing is require to know where to place the crossing tip. The problem is a half hearted attempt at cutting corners by using the more complex method, and it often ends in points that are not placed exactly as intended, due to being constrained by the crossing position. A pre made frog is no better or worst than any if correctly made, off board or on the baseboard, but from what I have seen dozens of times is that it can lead to having to adjust the intended course of the track to get things into working clearances. It often results in kinks in the straight rails, relatively minor, or for glitches in the track course through the point. If it is a straight track and a simple fixed angle point, then all is easy, it can be calculated on a plot or template where every will go, but positioning the frog crossing first, and then gauging the track from that risks taking the perfectly straight outer rail, and having to gauge it to the frog, and that introduces a kink, albeit minor, and such a shift would be compensated for by laying the next pieces in line. But if the outer rail is laid straight, and the crossing is made related to the outer rail, then the main track through the point remains exactly where it was planned. The position of the crossing becomes a self finding one, it only has one position to go in, and the other tracks rails are the same, all the positions are determined from the exact course of the rails them selves, which are perfectly in gauge, and if you cannot get them in gauge........... This works for fixed crossing angles and for curved radius crossings in the same way. I have spent hours watching and helping out with points problems, especially PC construction, where I have despaired to see each part shifted about, fitted with gauges or not, to try to get things to line up, nearly always it is because the frog, (easier name) is in the wrong position, and attempts to correct the track around it fail miserably. When asked, it is often the reply that the crossing has to go there because the plan says so, or prototype dimensions are being copied. When you show them the course the centre of each track should take through the point the frogs are often 1/4 inch out on larger points. Yes, you can then adjust the rails to the frog, but the kinks are unacceptable. The perfect way would be to pre make the point off board, lay the approach track to plan, position the point in it;s entirety and then continue on laying the other tracks perfectly in line. But it may not exactly match a pre planned template, unless you are very expert at each stage. I think the better approach is to plan the track approaches and exits first, and use that to determine where the frog goes, it means kink free track and what I have always referred to as a ghost point, it is not there, it should not affect the stock passing over it, nothings perfect but that's what to aim for. The aim is different to the real thing, we are making working models, and that applies even in P4, where in the early days I saw an MRC member who pioneered P4 struggle with a point for two weeks to get it exactly as per prototype , only to end up with a less than perfect run through it. I re-did the whole thing in an evening for him, and he was very please that the stock now ran smooth, but the he complained that the frog was not in the position on the plan, it was from memory about 4 mm out, ..it turned out the plan was not as exact as he thought, and I am sure does not happen in computer generated plans. if the plan had been followed, and it had been, then you got a change in path f the wheels exactly were you don't want it, over the frog, and don't forget the slight change is reflected in the other wheels that are still clear of the frog, and the effect gives a twitch to the stock as it passes over the frog. I hope none of this is taken as an attack or complaint about various methods, I am just trying to say there are easy ways to get smooth running on models through points, and why it goes wrong sometimes. I should add another thing to check is how flat your point top surface is?? not often checked out on home made points of any variety, it should be checked out with a glass plate and engineers blue, it will surprise you how mainy warps and bumps are there, all adding to the rock and roll of going through a bad point, NO I do not check each one with glass, I just know the faults are possible, and take extra care and check with a steel rule. good enough once experienced or taught it can happen. I will later post some assembly shots etc but at the moment still having treatment for a left arm and hand affected by arthritis, so a bit restricted on home made points, and using RTL Peco etc., for the Brewery layout in 00. Link to post Share on other sites More sharing options...
Brian Harrap Posted January 13, 2017 Share Posted January 13, 2017 When I'm feeling a bit Devilish, I have been known to use a Lego brick as a track gauge.B Link to post Share on other sites More sharing options...
RMweb Gold martin_wynne Posted January 13, 2017 RMweb Gold Share Posted January 13, 2017 I have never used check rail chairs either. These seem to fly in the face of setting the check rails using gauges Using check chairs you gauge to the check rail, and let the stock rail take care of itself. regards, Martin. Link to post Share on other sites More sharing options...
jim.snowdon Posted January 13, 2017 Share Posted January 13, 2017 I have never used check rail chairs either. These seem to fly in the face of setting the check rails using gauges, and are only viable - with no adjustment/fettling possible - if the stock rail is perfectly gauged from the crossing. Which brings us back to the begining.........all swings and roundabouts. regards, Izzy All the pointwork I have built in 0-MF (31.5mm gauge) has used alternating full and half chairs through the check rails, with the checks set by gauge from the crossing. Check chairs are not currently available in 7mm scale, other than possibly from the likes of Shapeways, and I remain to be convinced that even in the larger scale I could actually see the difference between a sngle piece check chair and a "chair and a half" without examining the track from a distance that is impracticably close. Jim Link to post Share on other sites More sharing options...
jim.snowdon Posted January 13, 2017 Share Posted January 13, 2017 It is indeed swings and roundabouts, it works both ways, but I think for points that involved a curved route through them, the most commonly used in models to save space, the datum is the track course, and the crossing is fitted exactly where it has to go, +/- nothing, aided by precise gauging and nothing else. The pre building of a standard crossing with a fixed angle is quite different, the crossing becomes the datum for the measurements, and governs where the outer rails are laid, therefore very precise per planning and plan printing is require to know where to place the crossing tip. The problem is a half hearted attempt at cutting corners by using the more complex method, and it often ends in points that are not placed exactly as intended, due to being constrained by the crossing position. A pre made frog is no better or worst than any if correctly made, off board or on the baseboard, but from what I have seen dozens of times is that it can lead to having to adjust the intended course of the track to get things into working clearances. It often results in kinks in the straight rails, relatively minor, or for glitches in the track course through the point. If it is a straight track and a simple fixed angle point, then all is easy, it can be calculated on a plot or template where every will go, but positioning the frog crossing first, and then gauging the track from that risks taking the perfectly straight outer rail, and having to gauge it to the frog, and that introduces a kink, albeit minor, and such a shift would be compensated for by laying the next pieces in line. But if the outer rail is laid straight, and the crossing is made related to the outer rail, then the main track through the point remains exactly where it was planned. The position of the crossing becomes a self finding one, it only has one position to go in, and the other tracks rails are the same, all the positions are determined from the exact course of the rails them selves, which are perfectly in gauge, and if you cannot get them in gauge........... This works for fixed crossing angles and for curved radius crossings in the same way. Every one will have their own way of building pointwork, and there is no absolute right or wrong method, so this is not a criticism of anyone in particular. Our current club 0 gauge layout, for which I designed the track layout, is a continuous curve, with the result that all of the turnouts are curved through both legs, with crossing angles that are whatever is needed to fit the geometry. I drew the lot out using AutoCAD (and doubtless Templot would do just as well - I just happen to have AutoCAD) and printed the templates from that. For the really complex bit, which contains three trailing crossovers in a row, one of them with a diamond in the middle, I got the whole thing printed as a single sheet and stuck that to the baseboards. The crossings I made up as separate units on local copies of the template and installed them as the first item in each turnout, then built around them. The diamond was built the same way, but as a complete unit, ie all four crossings, as the gauging and flangeways through the two obtuse crossings are particularly critical to getting the wheels to check properly, as these crossings cannot have conventional check rails. Jim Link to post Share on other sites More sharing options...
RMweb Gold martin_wynne Posted January 14, 2017 RMweb Gold Share Posted January 14, 2017 For those fretting about the precision of their track building, this is the way the prototype does it: Martin. Link to post Share on other sites More sharing options...
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